Process of dephosphorizing iron by means of oxides of iron



UNITED STATES PATENT OFricE.

, JACOB REESE, OF PITTSBURG, PENNSYLVANIA.

PROCESS OF DEPHOSPHORIZING IRON BY MEANS OF OXIDES OF IRON.

SPECIFICATION forming part of Letters Patent No. 349,744, datedSeptember 28, 1886.

I Application filed August 23, 1883. Serial No.. 101,532. (No s1ecimens.)

To all whom it may concern.-

Be it known that I, JACOB REESE, a citizen of the United States,residing at Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Process of DephosphorizingIron by Means of Oxides of Iron; and I do hereby declare the fol lowingto be a full, clear, and exact description thereof.

The improvement consists in the formation of a non-calcareous basic slagin Bessemer converters and similar refining-chambers, and in effectingthe removal of the phosphorus from the metal into the slag.

A highly refractory calcareous slag formed by the use of lime liningsand lime additions is employed in the basic process as at presentpracticed. The weight of the lime additions runs from twenty to thirtyper cent. of the weight of the metal, and the large quantity ofrefractory slag formed thereby tends to and in some instances does chillthe metal. The slag is also apt to form troublesome accretions to thelining of the converter. In my present invention I propose to overcomethese defects by producing and using an oxide-of-iron basic slag whichwill be more fusible, more liquid, can be used in less quantity, and canbe run quickly in a highly fluid state into the converter.

In the practice of the basic process it has been found that the electiveaffinity of the phosphorus during oxidation is for oxide of iron, andafter oxidation it is initially held as a phosphate of iron in thecalcareous slag. If the slag is of ahighly calcareous basic nature, thephosphate of iron may be decomposed and a phosphate of lime formed. Inthe practice of my invention I therefore propose to make mynon-calcareous basic slag by the use of oxide-of-iron linings andoxide-of-iron additions to the converter. The quantity of the oxideadditions will be less than in the use ofa calcareous'slag, first,because the slag will be more fusible and be thoroughly admixed with andwash the metal; second, on account of being its first elective affinitythe oxide-ofiron slag will take up a greater percentage of phosphorusbefore saturation is effected. The use of the oxide-of-iron slag mayalso prove more advantageoua because, being in a very highly fluidcondition, it cannot entangle and hold in mechanical suspension aslargean amount of particles of metal as is held at the close of the blow bythe calcareous slag. Further, as the slag will be highly fluid, less ofit will be mechanically held in the metal at the end of the blow.

In the practice of my improvement Ifirst form an oxide-of-iron lining inthe converter, which may be done by melting oxide of iron as free aspractical from silica and phosphorus in a suitable cupola or furnace,and then' casting the fluid oxide into the converter and around asuitable core, thus forming a lining consisting of a single mass ofhard, close, and dense oxide of iron. The bottom lining is then formedin a similar manner, the cores are withdrawn and the bottom adjusted,and the converter got ready for operating. A charge of metal is then runinto the converter and an addition of from ten to twenty per cent. ofmelted iron ore (compared with the weight of the metal) is run into theconverter. The airblast is then turned on and the blow is continued inthe usual manner until the phosphorus is removed from the metal into theslag. In conducting this operation the phosphorus is eliminated underthe following conditions: If it abide as phosphorus in the metal, itwould become oxidized to phosphoric acid, which would pass up and unitewith oxide of .iron, (its first elective affinity,) and thus form ofiron chemically combinedthen both are oxidized together, forming thephosphate of iron, which is taken up and retained by the slag. Theamount of oxide-of-i.ron additions necessary will vary in proportion tothe varying amounts of silicon and phosphorus present in the metaltreated by the different blows, as is now the ease with lime additionsin the .use of the calcareous basic process, but will run at leastone-third less in weight than the additions used in the latter process.

As the linings used in carrying out my improvement are not of a highlyrefractory na ture, it is necessary to conduct the process in an air orwater jacketed converter to maintain the lining below its point offusionsueh,- for instance, as shown and described by me in anapplication filed June 4,1880, Serial No. 35,514, for converting crudecast-iron into cast-steel.

I am aware of English patent of Talabot, No. 370 of 1857, in which themetal is subjected to the action of air-blasts while in a chalk or chalkand oXide-of-iron lined vessel but in this patent the metal is nottreated in the presence of oxide-o'f-iron additions, and it is notadmissible to suppose that suflicient oxide of iron would be formed bythe oxidation of the metal, as it will require from. ten. to twenty percent. of oXide-of-iron additions, and to produce such a large amount bythe oxidation of the metal would be destructiye to the economy of theprocess.

I am also aware of Englishpatents of Henderson, 1,051 of1870 and 2, 9:40of1870, in which oxide of iron .and finer-spar are used as a lining andslag. A lining of this character is not practical, as fluorspar is oneof themost powerful fluxes known to metallurgists, and would have atendency to flux the oXi(le-of-iron lining down at a temperaturecertainly below 2,000 Fahrenheit, while a temperature of 4,500 is anessential condition of my process, and the presence of fluorine orfluorine spar would be destructive to my lining and the process.

blowing the metal in the absence of carbon and in the presence of anon-calcareous basic slag until the phosphorus is eliminated from themetal by oxidation and held in the slag as a phosphate, substantially asset forth.

2. The step of forming a non -ealeareous basic slag, which consists inblowing molten metal with an air-blast while held in an oxide Uof-iron-lined vessel, and in the presence of from ten to twenty percent. of oxide of-iron additions, until a fluid non-calcareous basicslag is formed, substantially as set forth.

JACOB REESE. \Vitnesses:

WVALTIJR Rnnsn, O. 0. LEE.

